Fabio Capello was at this game to watch Theo Walcott – he could hardly have been interested in anyone else in the starting line-ups – and he will have been pleased by what he saw. The Arsenal manager was certainly happy with his player, despite Blackburn restricting his opportunities much more effectively than Blackpool managed last week.

"Theo was not on the ball as much this time, but what do you want from a striker?" Arsène Wenger said. "You want him to make the most of the chances that come his way. We had fewer opportunities than last week, but he was still sharp and he supplied a clinical finish. It looks to me like Theo is playing with more confidence."

Walcott scored an excellent goal in the first half and was unlucky not to add a second near the end with a confident drive from outside the area that only just cleared Paul Robinson's bar. Capello will not be concerned about whether Walcott has a football brain or not, to quote the debate started by Chris Waddle last season, he will just have noted that he is running, shooting and finishing with poise and self-belief.

Both sides could have scored in a frantic start to an open game. Arsenal were unlucky not to go in front in the third minute when Abou Diaby's shot through a crowded penalty area was stopped on the line by Vince Grella, who was relieved to see the rebound cannon from his shin onto Robinson's shin then out to safety, rather than off the goalkeeper and into the back of the net. Then after Blackburn applied some pressure and won a couple of corners, Ryan Nelsen's goalbound header was headed off the line by Cesc Fábregas.

It took a good interception by Chris Samba to prevent Fábregas sending Walcott clear a couple of minutes later, though Blackburn's respite was brief. Robin van Persie took a pass from Andrey Arshavin and found Walcott quite brilliantly with a diagonal ball behind Gaël Givet. The finishing prowess evident last week against Blackpool was displayed again as the winger strode onto the ball and clipped a low, early shot past Robinson's dive. Walcott found Robinson's bottom right corner so perfectly, in fact, that the side-netting needed a minor repair at half-time. He had gone for placement rather than power, yet still managed to burst the net.

Unlike a few of their north-west neighbours, Blackburn are not the sort of side to lie down and take a hammering, however, and though Arsenal briefly threatened to run riot, they found themselves defending for most of the rest of the half after a smartly taken equaliser. Rovers now boast two Dioufs in their ranks, Manchester United's Mame Biram having arrived on a season's loan to join the already established El Hadji – and Laurent Koscielny in particular will not forget the way they combined in the 26th minute. Seizing on Samba's clearance, El Hadji took on the French defender on the outside and won hands down, staying on his feet despite a heavy challenge and supplying a cut-back from the byline that Mame Biram only needed to tap into the net for his first Premier League goal for his new club, after a Carling Cup hat-trick against Norwich in midweek.

Big, strong and mobile, with an ability to deliver a good cross as well as get on the end of one, the new Diouf looks exactly like Sam Allardyce's sort of player and when Benjani Mwaruwari joins the attack – he has signed for a year after his contract expired at Manchester City – Blackburn should be able to bother quite a few defences.

Arsenal's attack lost some of its sharpness when Van Persie went off with a twisted ankle just past the 30-minute mark after a firm, but fair, tackle by Phil Jones, though the visitors were still potent enough to take the lead again early in the second half. Bacary Sagna got away down the right to set up Fábregas for a shot that was blocked and, as Robinson left his line to claim the rebound, he was beaten to the ball by a determined Arshavin.

Blackburn could not manage a second equaliser. Substitute David Dunn had the best opportunity 10 minutes from time, but having made space for a shot he directed it straight at Manuel Almunia. When Arsenal had a chance to make it three right at the end, with Walcott unselfishly setting up Jack Wilshere, Robinson denied the young England hopeful. Capello was probably on his way to Blackpool by then in any case.

Allardyce said he was disappointed, though he actually looked more resigned. He did have a point in claiming Blackburn did not do quite enough to win the game in the first-half period when they were in the ascendancy. Wenger admitted they had Arsenal rattled, Allardyce bemoaned the fact they were not quite sharp enough to take advantage. Maybe the experienced Benjani can help in that respect. "We exposed them defensively several times in the first half, but we couldn't quite find the finish or the final ball," the Blackburn manager said.

"That was our chance to get our noses in front and, when we didn't take it, there was always the possibility that Arsenal would take control. Switch off for just a second and they punish you, because they have the quality. I could criticise my defenders for the goals conceded, but the first one especially was superbly made. That sort of quality is very difficult to do anything about."

THE FANS' PLAYER RATINGS AND VERDICT GORDON MOULDEN, Observer reader I can't complain about the result – we lost to the better team, although both goals could be put down to lapses of concentration, Jones for the first goal and El Hadji Diouf for the second. Every time we made a substitution we got worse, whereas when Arsenal made changes, you couldn't even tell. That's the difference between the big clubs and the likes of us. Mame Diouf was our most effective attacking player today and El Hadji Diouf has started the season well, but as Dunn is so injury-prone we need a creative player to link the midfield and attack. Whether we can afford one or not is a different matter.

BEN LOVER, Observer reader We're absolutely delighted with the win. The main challenge was always going to be Blackburn's aerial threat and I thought we coped with that very well – Vermaelen marshalled what was a fairly inexperienced defence. We had a slightly shaky start but completely controlled the second half – I don't think Almunia had a save to make. Walcott was excellent again, he's developed the confidence to try something different and the Blackburn defence was scared of him. I think our squad is looking strong, we now have players who can come in without weakening the team and that's a big improvement on last season.